If D2D enabled nodes or UEs are in proximity to each other, they may be able to use a “direct mode” (e.g., as in FIG. 1) or “locally-routed” (e.g., as in FIG. 2) path for data communication, unlike in the conventional cellular communication (FIG. 3). In such so-called device-to-device communication, the source and the target are wireless devices or D2D enabled nodes, e.g., UEs. Some of the potential advantages are off-loading of the cellular network, faster communication, increased awareness of surrounding wireless devices of interest (e.g., running the same application), higher-quality links due to a shorter distance, etc. Some appealing applications of D2D communications are video streaming, online gaming, media downloading, peer-to-peer (P2P), file sharing, etc.
A more detailed example reference architecture for D2D operation is illustrated in FIG. 4.
A D2D enabled node of a wireless communication network like, e.g., a UE, may not be able to receive cellular signals and D2D signals simultaneously and may miss one or both types of signals if they are received by the D2D enabled node or UE during the same or overlapping time period. The network node serving the D2D enabled node or UE may not even be aware of such loss of signals and may cause excessive delay in delivering data to the UE.